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Heart Attack

Last updated May 22, 2021

Reviewed by: Mbu Mongwa, MD

Approved by: Krish Tangella MD, MBA, FCAP

A Heart Attack occurs when the flow of oxygen-rich blood to a section of the heart muscle becomes obstructed. If the flow is not restored quickly enough, then that portion of the heart muscle begins to die.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Acute Coronary Syndrome
  • Cardiac Infarction
  • Coronary Vascular Occlusion

What is Heart Attack? (Definition/Background Information)

  • A Heart Attack occurs when the flow of oxygen-rich blood to a section of the heart muscle becomes significantly impaired. If the flow is not restored quickly enough, then that portion of the heart muscle begins to die

Heart attacks occur when blood flow to an an area of heart muscle is interrupted, usually suddenly. Most typically, this is a result of sudden plaque rupture. Plaque are soft tissue deposits on the inner surface of the heart's blood vessel containing various cell types and lipids including cholesterol. The plaques may become unstable and suddenly break off. Fragments may then lodge further downstream in the blood vessel, interrupting the blood supply and it's oxygen transport to muscle tissue down stream. This causes the infarction (death) of the muscle tissue or, a heart attack. Clots may also form at the point of plaque rupture, similarly occluding the blood vessel.

Much less commonly, the vessels may be occluded by spasms of the coronary (heart) blood vessels or from a clot carried in from the heart.

Who gets Heart Attack? (Age and Sex Distribution)

  • Heart Attacks usually occur after age 45 years in men, and above 55 years in women. However, it can occur in much younger individuals depending on the risk factors
  • Also, it has been noted that men are more affected by this condition than women
  • There are no racial/ethnic or geographical preferences, all groups are equally affected by this condition, depending on their risk factors

What are the Risk Factors for Heart Attack? (Predisposing Factors)

The risk factors for Heart Attack may include:

  • Smoking: The longer is the smoking history (in pack years), the higher is the risk
  • High blood pressure (BP): The longer the duration and the higher the level of BP, the greater is the risk
  • High blood cholesterol (total cholesterol) with low HDL cholesterol (good cholesterol) and high LDL cholesterol (bad cholesterol). Decreased levels of LDL are associated with an increased risk of Myocardial Infarction
  • Obesity - higher levels of obesity is associated with an increased Myocardial Infarction risk
  • An unhealthy diet that is high in saturated fats and trans-fat, cholesterol, and sodium
  • Lack of a regular physical activity (living a sedentary lifestyle)
  • High blood sugar due to diabetes (poorly-controlled diabetes) or due to insulin resistance
  • An advanced age
  • A family history of heart attack, particularly if the individual’s father/brother had any heart disease before age 55 years, or if their sister/mother had a Heart Attack before age 65 years
  • Preeclampsia: This condition develops in pregnancy; the key signs being a rise in blood pressure and excess protein in urine. It is linked to an increased risk of serious heart-related medical issues such as coronary artery disease, Heart Attack, and heart failure
  • After the first incidence of a Heart Attack, the chances of a second Heart Attack are higher

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Heart Attack? (Etiology)

A Heart Attack occurs when the flow of oxygen-rich blood to a section of the heart muscles suddenly gets interrupted.

  • Coronary arteries supply oxygenated blood to the heart musculature. Coronary artery disease is the leading cause of a Heart Attack. It is a condition in which waxy, cholesterol-rich substances called plaque, build up on the inside walls of the coronary arteries. When a plaque ruptures, a blood clot may form at the site of rupture. If this clot is large enough, it may block the artery completely. If the blockage is not treated soon enough, then a portion of the heart muscles, which are fed by the artery, begin to die. Dead heart tissue is subsequently replaced by scar tissue
  • A less common cause of Heart Attack is coronary artery spasm (tightening of the muscle of the artery resulting in blockage). This may occur due to the usage of certain illegal drugs (such as cocaine), emotional stress, pain, exposure to extreme cold, or cigarette smoking. A coronary artery spasm leads to a lack of blood supply to the heart muscles causing death of the muscles

What are the Signs and Symptoms of Heart Attack?

The signs and symptoms of a Heart Attack may include:

  • Sudden, severe, crushing, and squeezing chest pain/discomfort
  • Also apparent may be a change in the pattern of existing chest pain with discomfort. The discomfort is in the center or left side of the chest, and it often lasts for more than a few minutes, alternately leaving and returning
  • Heart Attack pain can sometimes feel like an indigestion or a heartburn
  • Discomfort felt in the upper body region; in a single arm (or both arms), the neck, jaw, back, or upper part of the stomach
  • Shortness of breath that may occur before or with the chest discomfort
  • Sweating, which may be very profuse (breaking out into a cold sweat)
  • Palpitation (feeling that the heart is beating too fast or irregularly), fainting, cough, or anxiety
  • Nausea, lightheadedness, sudden dizziness, or vomiting
  • Sleep problems, fatigue (tiredness and lack of energy feeling)

How is Heart Attack Diagnosed?

A Heart Attack is diagnosed based on the signs and symptoms, medical and family history, and other diagnostic test results. These include:

  • Electrocardiogram (EKG): This test records the electrical activity of the heart. It can show signs of a previous or current Heart Attack
  • Blood tests: Blood tests. such as troponin test, CK-MB test, and serum myoglobin analysis, are used to measure elevated amounts of certain proteins in the bloodstream. During a Heart Attack, when the heart muscle cells die, these proteins are released from the injured or dead heart muscle cells into the bloodstream and can be detected by the tests
  • Coronary angiography: This test, often performed during a Heart Attack, uses a dye and special X-rays to evaluate the course of the coronary arteries, and to detect any significant blockages
  • Myocardial stress testing (stress test of the heart): Studies may be performed to determine blood flow in the coronary arteries of the heart. This assessment of blood flow can either be performed using a treadmill exercise test or using a pharmacologic stress test of the heart
  • In a treadmill exercise test, an individual is made to walk or run on a treadmill. Slowly the intensity of the exercise is increased. During this test, the heart is monitored looking for any abnormal function on an EKG. Once a significant abnormality is observed on EKG, the treadmill stress test is stopped by the physician. There are diagnostic criteria which when met, may indicate a low risk level or high risk level stress test with significant abnormalities. With the latter, a more definitive evaluation of the coronaries, usually with coronary angiography, will then be pursued. In general, a lower exercise tolerance usually indicates a more severe coronary artery disease
  • A pharmacologic stress test is performed on an individual, who cannot be tested on a treadmill exercise test. This may be because of limitations in the patient gait or certain baseline characteristic features of the patient’s baseline ECG which limit its interpretability during stress.  In one form of this test, a drug that increases the heart rate is administered. This drug increases the heart rate, stimulating it like one would see during an exercise. Abnormalities observed in the EKG, similar to those obtained with exercise, indicate the presence of a coronary artery disease. Another stress test measures the supply of oxygenated blood to different heart muscle territories supplied by the coronary arteries during stress and indicates if the blood supply appropriately increases with stress or fails to do so, indicating disease in the muscle area supplied by the diseased coronary artery

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Heart Attack?

The possible complications that arise from a Heart Attack include:

  • Heart failure, both acute and chronic
  • Aneurysm or rupture of the myocardium, due to tissue damage
  • Mitral valve regurgitation caused by a rupture of the papillary muscles, which is attached to the mitral valve
  • Arrhythmias (irregular heart rhythm), which may originate in the atrium or more frequently in the ventricle, including arrhythmias such as atrial fibrillation, ventricular tachycardia, and ventricular fibrillation
  • Long-term complications include heart failure and increased risk of Myocardial Infarction (Heart Attack).

How is Heart Attack Treated?

A Heart Attack is a medical emergency. Call 911 or your local medical emergency number for healthcare in your area. A variety of medications may be given right away to improve circulation of the coronary arteries supplying blood to the heart. These include:

  • Sublingual (below the tongue) nitroglycerine administration
  • Oral aspirin
  • Betablockers
  • Ace inhibitors
  • Anticoagulants or blood thinners
  • Antiplatelet drugs

Other measures include:

  • Percutaneous coronary intervention (PCI), to open up the blockage site, and if indicated (as is most often the case), a stent is placed at the site of artery blockage
  • Fibrinolysis with clot-busting medications is recommended in those with one type of Heart Attack, called STEMI (ST-Elevation Myocardial Infarction). ST indicates the ‘S’ and ‘T’ wave present on an EKG, as part of the PQRST electrical wave complex, which occurs during the single beat of the heart
  • Oxygen therapy, using higher concentrations of oxygen
  • Surgery, such as coronary artery bypass grafting (CABG), may also be used to treat a Heart Attack. Here, a healthy artery or vein is connected/grafted to the blocked coronary artery restoring blood flow downstream of the site of the blockage

How can Heart Attack be Prevented?

In many cases, Heart Attacks may be prevented by considering the following:

  • Heart healthy lifestyle: This includes having a healthy diet mostly consisting of whole grains and fruits and vegetables, with poultry, fish, lean meat, milk, and milk products should be low-fat or fat-free
  • If overweight or obese, then physical activity and diet may be employed to maintain a reasonable weight loss plan. Being physically active can improve fitness and health
  • Cessation of smoking
  • Paying attention to and keeping in control other medical issues such as diabetes, high blood pressure, and high blood cholesterol

What is the Prognosis of Heart Attack? (Outcomes/Resolutions)

The prognosis of a Heart Attack varies greatly. It depends on the individual’s health, the extent of the heart damage, and promptness with which medical treatment is administered.

  • If heart damage is extensive, then complications, such as heart failure and arrhythmias, may occur that could be life-threatening. Moreover, after a first attack, the chances of a second Heart Attack is significantly higher
  • Prompt medical therapy in a mild Heart Attack can result in an excellent prognosis. On the other hand, delayed medical attention for an individual with severe heart disease may result in poor prognostic outcomes

Currently, excellent treatment measures are available for Heart Attacks such that they save lives and greatly mitigate long-term complications and ensuing disabilities.

Additional and Relevant Useful Information for Heart Attack:

  • Heart Attacks along with strokes (collectively referred to as cardiovascular diseases) are leading killers of both men and women around the world
  • Cardiac rehabilitation is a medically-supervised program to help improve the health and well-being of individuals with heart-related medical issues, and to also reduce the future risk of a heart condition

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Oct. 2, 2013
Last updated: May 22, 2021